Amplitude



Oct. 9, 1928. 1,687,061 H. J. J.- or; R. DE BELLESClZE ANTIPARASITE RECEIVER FOR WIRELESS COMMUNICATION SYSTEMS AMPLITUDE AMPLlTUDE 5|6NAL TIME AMPLITUDE a. 115 W. l4: & nME AMPLITUDE F 2 JLfin l al-" TIME CURRENT GRID VOLTAGE Eivwemtor HENRI J.J NLDER. DEBELLESCIZE 335% MW fbkozmggXQ Oct. 9, 1923. 1,687,061

H. .J.'M. DE R. DE BELLESCIZE ANTIPARASITE RECEIVER F03 WIRELESS COMMUNICATION SYSTEMS Filed June 1923 2 Sheets-Sheet 2 amnwco'z HENRi J. JM. DER. DE BELLESUZE 1 I 7 351 hms pz meg gaadw Patented (let. 9, 1928.

UNITE HENRI JEAN JOSEPH DE ltEG-l llill'llifl nit BELIEJEEEGIEE, OF Illtlllt'fi,

ANTIPARASITE REGEIV FtlIt i;

' UQTHBQTUNTCACTION Application filed June 9, 19533, herial No. erases, and in France July 21, 1922. I

The present invention has for its object the provision of an improved receiver applicable to Wireless communication Sf. ems and making possible the elimination of damped disturbances the initial amplitude of Which is very much greater than that of the signal which it is desired to receive.

The receiver forming the object of the present invention comprises arrangements described in the following, tWO patents of the same inventor:

U. S. Patent No. 1,443,011 atmospheric disturbance reducing means.

U. 53. Application, Serial l lo. 624,286, filed March 10, 1923, oscillation control.

The essential characteristic of the present invention consists in the combination of the arrangements forming the objects of the above mentioned patent and. application with new arrangements to be hereinafter described.

lin the drawing,

Fig. 1 represents the various stages of a disturbing train of oscillations in my in vention,

Fig. 2 shows the characteristic of vacuum tube as used in my invention,

Fig. 3 shows a Way of connecting a tube so as to obtain the desired characteristics, and

Figs. 4i and 5 are tWo forms of receiver according to my invention.

The receiver forming the object of the present invention comprises the following; elements:

A-An open or closed antenna followed eventually by a certain number of high frequency resonators. an amplifier, a detector, a 10W frequency filter and damping); tubes.

B-A limiting arrangement for preventins; the oscillations from exceeding the amplitude of the signal.

C-One or a plurality of circuits Which may be aperiodic or in resonance with the modulation frequency of the signal and the time constant of Which is adjusted to as high a value as the speed of signal transmission permits.

D-A tube the grid potential of which is normally adjusted to a value which i slisghtly more negative than the value neces.-.ary for annulling the plate current but Whose amplification is Worked out in such a manner that the signal Will impart to this grid of the drawing which shows, by Way of example,

the invention applied to a radio receiving circuit. The receiver has a closed antenna circuit, including; the inductance l, and variable condenser 52. @scillati'ons received in this circuit cause corresponding oscillations in a resonant circuit comprising inductance 3 and. variable condenser The oscillations are then amplified by any desired. means, represented conventionally by 11, and detected by the tube is, having in its grrid circuit the condenser 12 and grid leak The lied currents in the output circuit of tube 14:, traverse resistance 2i and, thereby, increase the plate potentialot tube l l, these increases being suitably controlled by the adjustable contact 7 forming the battery connection. The resulting oscillations are transmitted through a low frequency filter provided for the purpose of preventing the return of high frequency oscillations to the grids of the damping tubes. The filter is represented diagraminatically by the elements 8, 9 and 10 and is connected on its output side to the tWo tubes 5, the filamentplate circuit of one of which is connected across the antenna circuit 1-2 and the filament-plate circuit of the other of Which is connected across the resonant circuit 34i-. This device operates as explained in the patent and application above referred to, to increase the damping (if disturbing oscilla- 'tions.

The apparatus thus far described comprises the element A. of the system and serves to reduce the duration of all parasitic trains of impulses Whose amplitude exceeds that of the signal. llf let alone tl ese trains would have the form of the curve Q3 in 1, but due to the operation of this apparatus they assume the form indicated by Q These oscillations now having); the form indicated by in Fig. 1, are impressed on the input circuit of tubes 23 and 26 conin cascade which, together with nected 7 their circuits. comprise the element B of the system and serve to limit the amplitude of the disturbing oscillations in their output circuits. Due to a suitably selected grid which i less than that of the signal.

potential, the tube 23 transmits the oscillations withoit deforming them and the oscillations will. be translated with a reduction of potential at the top of resistance 24;. ihe grid potential of tubefZG is adjusted by means of movable contact 25, forming adjustable battery connectioin to such an initial value that the signal. will cause plate current of this tube to fall nearly to Zero whereby, no matter what the force of a disturbance may be, it will also be recuced to the same value. lhis reduction in amplitude changes the form of the disturbance from that shown as in Fig. 1 to that shown in Q3.

This element and 'ts func ion form an important feature of the invention and will be described more in detail hereinafter.

The oscillat'ons now impressed on a circuit, comprising a resistance d variable capacity 31. which should lo a high as permitted by the sending spec l. The larger this capacity the less will be he difference of potential caused by a given disturbance. T his circuit comprises the element C of the system and, owing to its high time cons 'ai t, the parasiic train at its output is clongatec as to time but its amplitude falls to a value In its passage through. this circuit the disturbing oscillation will be changed from the form represented by Q in Fig. l to that represented by The amplitude of the disturbing oscillations is then further reduced to negligible value by means of the tube 43 which with its grid resistance l2, its adjustable battery connection -1 and the associate circuits. coniprises element D of the system. lhe effect of this unit is to change the form of the disturbing oscillation from that shown L s O in Fig. l, to that shown as The operation of this unit will also be described in considerable detail hereinafter, as it comprises a very important feature of the invention.

The output circuit of the tube 43 is connected to any desired signaling; means. In the drawing. this output circuit includes a registering device 51 and resistance 02 in series. The potential across the resistince 52 causes current flow in the telephone receiver 5i, interrupted by a musical. vibrator 53. The receivec signals can then be vi. ually and audibly indicated.

Referring to Fig. 1 it snould be noted that the weakening of the disturbances has the two following phases:

First: reduction from Q to by diminishing; the duration followed a limitation of the amplitude. After this reduction the quantity of electricity comprised between the curve (al and the axis of time will be less than that generated by the signal.

Second: reduction from Q to Q by pas the other hand the ellect 'if an increase in the limited by the cruvhture of the grid rliaractci'istie. 'lhc circuit arrangement consists in iutrinlucinit a very iigh resistance ll (e. 5;. several. megohms) in series with the grid of the tube in ques 'on (Fig. The operation is as follows: Assuming a certain potential for the plate battery, RY (l? 151 2) and (7% are the curves which show the plate and grid currents as functions of the grid potcntial.

If the grid potential negative then the grid current will be zero and the tube will operate as though the resistance ll did not exist. That part of the characteristic which is to the left of the axis of cur rent will not be modified.

Let us assume however, that the grid circuit is subjected to a positive imtential V the grid current boil other than zero; a drop of 1;)\ tential will then be caused in the resistance in such a manner 'hat the cl? fective value of the grid potential, will d rop V In the graphical illustration in 2, we ma trace point by point the new 3c. the angle 0: being re- (tan a L The plate curi"-nt il'ollm therefore omy the grid potentials coinpriJcd between Zero and a. certain negative valur which may be brought near to zero as desired by vuryin the potential of the plu battery.

The reduction of the amplitude of the distur anres in the second phase of the operation of the system is effected by the curvature of the plate cl aracteristic of tube if). The in'ti a1 potential of the rid is by means of amovable contact ll adjusted to a value OM (Fig. 2) which is slightly more negative than is absolutely necessary for annulling the plate current.

This arrangement will diminish the effect of the disturbance whose initial anmlitude has already been reduced by the prcccdng' devices in the circuit to a value V which is l ss than V the an'iplitude of the signal. llcferrin to Fig. 2 it will be noted that the plate current due to the grid voltage V due to the signal current and represented by TS is very much greater than that due to the tlu lib

ilt)

llll

the signal, is very much smaller than the ratio Y2 and the cllect oi? the disturb- B ances in the receiving device will be negligible as compared to the etl'ect ot the signal.

Finally the tendency of the signals to be cut up by parasites may be attenuated by introducing in the grid circuit the resistance 4-2 and by adjusting the amplification to a value which sutlicient tor the signals to develop in the resistance 32 a potential variation V which is suilicient to pass easily through the upper elbow of the new plate characteristic.

Fig. 5 shows an arrangement which is based on the same principle and is applied to receiving by means of a heterodyne 55.

The first limitation in the amplitude is obtained by means of the resistance 27 which inserted in the grid circuit ot the tube 23. The elongation out the disturbances is etfooted for the purpose of reducing their relative amplitude by means of the resonator 33 3 l which is tuned to the modulation trequency. By means oi. a variable reaction 36, the apparent decren'ient oil the resonator may be diminished, that is to say its time constant may be increased as much as the corresponding sending speed permits. Due to the provision of the tube 4:3 all the operations described in connection with Fig. l and also the rectification of modulated signals may be performed for the purpose of causing their recording by means of register 51.

Having described my invention, what I claim is:

1. The method of reducing the effect oft damped disturbances on electrical indicating apparatus which comprises the steps of convetting such disturbances into trains or impulses of less duration and amplitude, converting such shortened trains oit' impulses into trains of impulses of predetermined maximum value and converting such trains into trains of increased duration and decreased amplitude.

2. The method of reducing the effect on electrical indicating apparatus of atmospl eric disturbances normally giving rise to trains of impulses of relatively large magnitude and low damping, which consists of the steps of causing a decrease in the normal magnitude and an increase in the damp ing of such trains, lin'iiting the amplitude of such trains, and increasing the duration and decreasing the amplitude of such trains.

8. In a radio receiving apparatus, the combination cit an antenna, a tuned circuit coupled to said antenna, a detector coupled to said tuned circuit, means coupled to said tuned circuit to reduce the duration of an atmospheri impulse, means coupled to said detector o reduce the amplitude of said atmospheric impulse, means connected to said last mentioned means to increase the time duration of said impulse, and a second means coupled to said amplitude reducing means to further reduce the amplitude of the said impulse aiiter it has been increased in duration.

in a radio receiving apparatus an antenna, a detector associated therewith, a first means for varying the damping of the received osc'llations in accordance with the amplitude of detected currents and a second means associated with said first means for limiting the amplitude of disturbing oscillations.

5. ln radio receiving apparatus an antenna, a detector associated therewith, means associated with the detector for varying the damp oil the received oscillations in accordance with the amplitude of detected currents and means tor thereafter limiting the amplitude and increasing the duration of the damped oscillations.

6. In a radio receiving apparatus a tuned circuit and detector associated therewith, means associated with the detector for vary ing the damping ct said tuned circuit in accordance with the amplitude of detected currents, means associated with said first mentioned means tor limiting the amplitude of disturbing oscillations, and a circuit of high time constant for fur "her decreasing the amplitude oi the disturbing oscillations and increasing their duration.

HENRI JEAN JOSEPH MARlE de REGNAULD de BELLESCIZE. 

